1. Field of the Invention
The present invention is directed to a sheet feeding device, more particularly to a sheet feeding device which supplies a wide cutsheet that is greater than B5 in size on an endless belt, utilizing electrostatic absorption.
2. Related Background Art
Liquid injection recording devices (ink jet recording devices) which record text and images by delivering recording fluid from the recording head utilizing heat energy etc. are widely known.
These devices mainly use cutsheets such as sheets of paper or plastic as the recording sheet. This method emits low operational noise compared to other recording methods, and is superior in that its basic mechanical structures are simpler and inexpensive than other devices. This method has been employed in various fields, such as the fields of recording output devices for computers and word processors, for these reasons.
Presently, due to demands for high speed recording output the line type recording head which contains a printing area that covers the entire width of the cutsheet is being developed. This method attempts to accelerate the recording process by feeding the recording paper along a fixed recording head while maintaining the paper on a belt or an equivalent method of conveyance using procedures such as electrostatic adsorption etc.
However there are, special considerations required to prevent the belt from skewing in the orthogonal to direction the feeding direction, when rotating an endless belt which contains a width longer than the feeding orthogonal direction of the cutsheet.
One of the examples of a method for prevention of skewing is a method of moving the idle roller axis so that the belt returns to its original position, according to the skew amount for the belt detected by a sensor. This method is relatively trustworthy, but the device tends to become complex and expensive. Also, there is a problem of the printed character bending in the sub-scanning direction since the belt will be constantly repeat skewing in either direction when utilizing this method.
Another example is a method which causes a rib supplied on the inner side of the belt to correspond to the groove on the roller. Under these circumstances, virtually no skewing will occur, but the two disadvantages are that the belt will be expensive and the endurance will be negligible. This signifies that both of the above methods are unsatisfactory in either performance or endurance in spite of their complex devices and high costs.
Therefore, there is necessity for belt carriages that utilize the crown roller, which is the simplest method possessing the highest endurance. In this method, there is a necessity to increase the centripetal force of the belt using a larger crown to maintain as little skewing as possible, when the width of the endless belt is larger than the cutsheet feeding orthogonal direction, such as those endless belts containing widths which are larger than 200 mm, or those belts with low rigidity. Under these circumstances, there was a defect in that the unevenness of the intensity or scratches on the belt would cause buckling above the crown roller around the center of the belt, resulting in wrinkling and swelling of the belt.